In mammography, early detection of breast cancer is dependent upon the ability of the imaging system to resolve characteristic distributions and shapes of small microcalcifications in the breast tissue. Approximately 80% of excised breast cancers show areas of calcification on histologic examination. The medical community has not been satisfied with the imaging performance of standard film-screen or current digital imaging technology in its ability to produce the required high quality full field images. The research proposed here would enable the development of a novel imager by combining the high resolution and light output screen with a large-area modified structure a-Si:H detector for mammographic imaging procedures. Specifically we propose to develop large-area high resolution scintillator screens and low-noise a-Si:H detectors needed to carry out this objective. A digital detector system is being investigated that would potentially produce large format mammographic digital images with spatial resolution and detection efficiency superior to current film-screen systems. This system is based on a low-cost modified amorphous silicon (a-Si:H) architecture which takes advantage of the high specific light output of high resolution converter screens specifically designed for this system. In Phase I we successfully demonstrated the feasibility of the concept. In the Phase II project we will continue the research and development which will lead to the fabrication of a large area digital detector technology with a higher sensitivity, resolution, and dynamic range than existing digital systems. PROPOSED COMMERCIAL APPLICATION: Besides the enormous clinical X-ray imaging market, the proposed large area X-ray imaging system would find widespread use in instrumentation wherever high resolution X-ray radiography is used. X-ray radiography instruments currently have a very large commercial market. They may be applied to non-destructive testing systems, diffraction instruments, basic physics research, and other medical imaging systems.